4-Hydroxyalkyl-substituted 3-pyrazolidinone electron transfer agents

ABSTRACT

Photographic elements, film units, processes and alkaline processing compositions are described wherein certain 4-hydroxyalkyl-substituted 3-pyrazolidinones are employed as electron transfer agents in black-and-white and color image transfer materials. The silver halide electron transfer agents or precursors thereof have the following formula: ##STR1## wherein: n is 0, 1 or 2; 
     R represents hydrogen or a hydrolyzable moiety; 
     R 1  and R 2  each independently represents hydrogen, an alkyl or substituted alkyl group of 1 to about 6 carbon atoms, an aryl or substituted aryl group of 6 to about 10 carbon atoms, or an aralkyl group of 6 to about 10 carbon atoms, with the proviso that when n is 0, then either R 1  or R 2 , but not both, may be hydrogen; and 
     R 3  represents at least one alkyl or alkoxy group having from 1 to about 6 carbon atoms, methylenedioxy group or ethylenedioxy group.

This invention relates to photography, and more particularly toblack-and-white and color diffusion transfer photography wherein certainnovel 4-hydroxyalkyl-substituted 3-pyrazolidinones are used as electrontransfer agents. Post-processing D_(min) stability is thereby greatlyimproved in accordance with this invention.

Various formats for color, integral transfer elements are described inthe prior art, such as U.S. Pat. Nos. 3,415,644; 3,415,645; 3,415,646;3,647,437; 3,635,707; 3,756,815, and Canadian Pat. Nos. 928,559 and674,082. In these formats, the image-receiving layer containing thephotographic image for viewing remains permanently attached and integralwith the image generating and ancillary layers present in the structurewhen a transparent support is employed on the viewing side of theassemblage. The image is formed by dyes, produced in the imagegenerating units, diffusing through the layers of the structure to thedye image-receiving layer. After exposure of the assemblage, an alkalineprocessing composition permeates the various layers to initiatedevelopment of the exposed photosensitive silver halide emulsion layers.The emulsion layers are developed in proportion to the extent of therespective exposures, and the image dyes which are formed or released inthe respective image generating layers begin to diffuse throughout thestructure. At least a portion of the imagewise distribution ofdiffusible dyes diffuse to the dye image-receiving layer to form animage of the original subject.

Other so-called "peel apart" formats for color diffusion transferassemblages are described, for example, in U.S. Pat. Nos. 2,983,606;3,362,819 and 3,362,821. In these formats, the image-receiving elementis separated from the photosensitive element after development andtransfer of the dyes to the image-receiving layer has occurred.

U.S. Pat. No. 4,076,529 of Fleckenstein et al, issued Feb. 28, 1978,describes various color image transfer elements which employnondiffusible, redox dye-releasing (RDR) compounds which arealkali-cleavable upon oxidation to release a diffusible color-providingmoiety. An electron transfer agent (ETA) is oxidized as a function ofdevelopment. The ETA_(ox) then cross-oxidizes the RDR. The ETA compoundsdescribed therein include various pyrazolidinones, such as1-phenyl-3-pyrazolidinone, 1-phenyl-4,4-dimethyl-3-pyrazolidinone and4-hydroxymethyl-4-methyl-1-phenyl-3-pyrazolidinone. It would bedesirable to provide ETA's with better development rates or lowerD_(min) 's than those of the prior art.

In color transfer assemblages employing nondiffusible positive-workingredox dye-releasing (PRDR) compounds, a dye is released as an inversefunction of development, i.e., dye is released by some mechanism in thenonexposed areas of the silver halide emulsion. Use of anegative-working silver halide emulsion in such a system will thereforeproduce a positive image in the image-receiving layer. Examples of suchPRDR's are described in U.S. Pat. Nos. 4,139,379 and 4,139,389. Theimmobile compounds described in these patents are ballastedelectron-accepting nucleophilic displacement (BEND) compounds. The BENDcompound as incorporated in a photographic element is incapable ofreleasing a diffusible dye. However, during photographic processingunder alkaline conditions, the BEND compound is capable of accepting atleast one electron (i.e., being reduced) from an incorporated reducingagent (IRA) and thereafter releases a diffusible dye. This occurs in theunexposed areas of the emulsion layer. In the exposed areas of theemulsion layer, however, the ETA reduces the silver halide and becomesoxidized. The ETA_(ox) is then reduced by the IRA, thus preventing theIRA from reacting with the BEND compound. The BEND compound therefore isnot substantially reduced and thus no dye is released in the exposedareas.

After processing the photographic element described above containingPRDR's, ETA remains after imaging in both the exposed and nonexposedareas. A problem which occurs is that the D_(min) continues to increaseover a period of time. This is sometimes described in the art as"post-processing density increase". It is believed that over a period oftime, the ETA can slowly reduce the PRDR and cause this unwanted dyerelease. It would be desirable to provide ETA's which have betterpost-processing D_(min) stability in PRDR systems.

U.K. Pat. No. 542,502 discloses 3-pyrazolidinones with the 4-positionbeing monosubstituted. The particular substituent on the 4-position ofthe compounds of this invention is not disclosed in this patent,however. As will be shown by comparative tests hereafter, thissubstituent is one of the most important features of these novelcompounds.

U.S. Pat. Nos. 3,039,869, 4,209,580, 3,247,201, U.K. Pat. No. 2,073,734and Research Disclosure, Vol. 161, September 1977, Item 16139, page 26also disclose various 3-pyrazolidinones with various substituents.Again, however, the particular monosubstituted substituent on the4-position of the compounds of this invention is not disclosed in thesereferences.

It would be desirable to provide improved ETA's that have goodreactivity, relatively low stain, lower D_(min) 's, better developmentrates, good stability in highly alkaline processing compositions (i.e.,do not crystallize from or decompose in these compositions) and yetwhich will provide an improvement in post-processing D_(min) stability,over those of the prior art.

These and other advantages are provided by the4-hydroxyalkyl-substituted 3-pyrazolidinone compounds of this inventionwhich are silver halide ETA's or precursors thereof and which have thefollowing formula: ##STR2## wherein: n is 0, 1 or 2;

R represents hydrogen or a hydrolyzable moiety;

R¹ and R² each independently represents hydrogen, an alkyl orsubstituted alkyl group of 1 to about 6 carbon atoms such as methyl,ethyl, propyl, sec-butyl, hydroxyethyl, ethoxy, methoxy,N,N-dimethylaminoethyl or allyl; an aryl or substituted aryl group of 6to about 10 carbon atoms such as phenyl, p-tolyl, 2,4-xylyl,p-methoxyphenyl, p-carbonamidophenyl or p-hydroxymethylphenyl; or anaralkyl group of 6 to about 10 carbon atoms such as benzyl or phenethyl;with the proviso that when n is 0, then either R¹ or R², but not both,may be hydrogen; and

R³ represents at least one alkyl or alkoxy group having from 1 to about6 carbon atoms, such as methyl, ethyl, butyl, methoxy, ethoxy orpropoxy; methylenedioxy group or ethylenedioxy group.

R in the above formula can be hydrogen or any hydrolyzable moiety wellknown to those skilled in the art, such as acetyl, mono-, di- ortrichloroacetyl radicals, perfluoroacyl, pyruvyl, alkoxyacyl,nitrobenzoyl, cyanobenzoyl, sulfonyl, sulfinyl, or a blocking group asdisclosed in Mooberry and Archie U.S. Pat. No. 4,358,525.

When R in the above formula is hydrogen, the compound formula may bewritten in the keto form as: ##STR3## or in the enol form as: ##STR4##

As used herein, the keto form is meant to include the enol form and viceversa.

When R is the above formula is a hydrolyzable moiety, then the compoundis an ETA precursor and can be incorporated into a photographic element,cover sheet, receiving element, etc. Such compounds would be representedby the same general formula as above, except that "R" would be "R⁵ ",wherein R⁵ is a hydrolyzable moiety. During the processing of aphotographic element containing an ETA precursor, R⁵ will becomehydrolyzed by the alkaline processing composition to become hydrogen.When used in this manner, the ETA precursor can be employed in anyconcentration effective for the intended purpose. Good results have beenobtained when the ETA precursor is employed at a concentration of fromabout 0.05 to 2.0 mmoles/m² of element, preferably 0.1 to 1.5 mmoles/m².

ETA's directly incorporated into an alkaline processing composition willbe subject to hydrolysis, so that R in the above formula intrinsicallyrepresents hydrogen. When employed in an alkaline processing compositon,good results have been obtained when the ETA is present at aconcentration of from about 0.1 to about 30 grams per liter, andpreferably from about 2 to about 15 grams per liter.

In a preferred embodiment of this invention, R¹ is hydrogen or methyl.In another preferred embodiment of this invention, R² is hydrogen,methyl, isopropyl or phenyl. In yet another preferred embodiment of thisinvention, R³ is methyl or methoxy located in the para-position.

In addition to R³, the phenyl ring in the above formula may also besubstituted with any substituent as long as the photographic activity ofthe ETA is not impaired. Such other substituents include, for example,chloro, benzyl, dialkylamino or alkoxycarbonyl.

Examples of compounds useful as an ETA or precursor thereof inaccordance with this invention have the following formulae:

    __________________________________________________________________________     ##STR5##                                                                     Cmpd.                                                                         No. R        R.sup.1                                                                              R.sup.2                                                                              R.sup.3 n                                          __________________________________________________________________________    1   H        CH.sub.3                                                                             CH.sub.3                                                                             4'-OCH.sub.3                                                                          0                                          2   H        CH.sub.3                                                                             CH.sub.3                                                                             4'-CH.sub.3                                                                           0                                          3   H        H      CH(CH.sub.3).sub.2                                                                   4'-CH.sub.3                                                                           0                                          4   H        H      C.sub.6 H.sub.5                                                                      4'-CH.sub.3                                                                           0                                          5   H        CH.sub.3                                                                             C.sub.6 H.sub.5                                                                      4'-CH.sub.3                                                                           0                                          6   H        H      CH.sub.3                                                                             4'-CH.sub.3                                                                           1                                          7   H        H      H      4'-OCH.sub.3                                                                          1                                          8   H        H      H      4'-OCH.sub.3                                                                          2                                          9   H        H      H      4'-CH.sub.3                                                                           2                                          10  H        CH.sub.3                                                                             CH.sub.3                                                                             3',4'-OCH.sub.2 O                                                                     0                                          11  H        CH.sub.3                                                                             C.sub.6 H.sub.5                                                                      2'-OCH.sub.3                                                                          0                                          12  H        CH.sub.2 OH                                                                          CH.sub.2 OH                                                                          4'-OCH.sub.3                                                                          0                                          13  H        CH.sub.2 OCH.sub.3                                                                   CH.sub.2 OCH.sub.3                                                                   4'-OCH.sub.3                                                                          0                                          14  CO.sub.2 C.sub.4 H.sub.9                                                               H      C.sub.6 H.sub.5                                                                      4'-CH.sub.3                                                                           0                                          15  COCH.sub.3                                                                             H      CH.sub.3                                                                             4'-OCH.sub.3                                                                          1                                          16  CO.sub.2 CH.sub.2 C.sub.6 H.sub.5                                                      H      CH.sub.2                                                                             4'-OCH.sub.3                                                                          1                                          17  COCH.sub.2 C.sub.6 H.sub.5                                                             H      H      4'-CH.sub.3                                                                           1                                           18                                                                                ##STR6##                                                                               H      H      4'-CH.sub.3                                                                           1                                         19  H        H      CH.sub.3                                                                             4'-OCH.sub.3                                                                          2                                           20                                                                                ##STR7##                                                                               H      CH.sub.3                                                                             4'-OCH.sub.3                                                                          2                                         21  H        H      C.sub.6 H.sub.5                                                                      2'-OCH.sub.3                                                                          0                                          22  H        CH.sub.3                                                                             C.sub.6 H.sub.5                                                                      2'-CH.sub.3                                                                           0                                          23  H        CH.sub.3                                                                             H      3',4'-OCH.sub.3                                                                       1                                          24  H        C.sub.2 H.sub.5                                                                      H      3' ,4'CH.sub.3                                                                        1                                          __________________________________________________________________________

The ETA's described herein can be prepared by reaction of a substitutedhydrazine with a β-halogenated or β-hydroxy acid chloride or carboxylicacid as shown in U.S. Pat. No. 2,289,367 and EP No. 55,900, thedisclosures of which are hereby incorporated by reference. Anothersynthetic procedure involves transient blocking with a trialkylsilylgroup, addition of the desired electrophile in the presence of a strongbase, followed by removal of the blocking group by hydrolysis. This isdescribed and claimed in Michno U.S. application Ser. No. 520,283, filedof even data herewith, entitled PREPARATION OF 4-SUBSTITUTED3-PYRAZOLIDINONES, the disclosure of which is hereby incorporated byreference.

A photographic element according to this invention comprises a supporthaving thereon at least one photosensitive silver halide emulsion layerhaving associated therewith a dye image-providing material, andcontaining an ETA precursor according to the formula above where R is ahydrolyzable moiety.

A dye image-receiving element according to this invention comprises asupport having thereon a dye image-receiving layer and containing an ETAprecursor according to the formula above where R is a hydrolyzablemoiety.

A process for producing a photographic image in color according to thisinvention comprises:

treating an imagewise-exposed photographic element, comprising a supporthaving thereon at least one photosensitive silver halide emulsion layerhaving associated therewith a dye image-providing material, with analkaline processing composition in the presence of a silver halide ETAto effect development of each exposed silver halide emulsion layer,whereby:

(a) an imagewise distribution of dye is formed as a function of thedevelopment of the silver halide emulsion layer; and

(b) at least a portion of the imagewise distribution of the dye diffusesout of the element, such as to a dye image-receiving layer.

In the above process, the ETA may be located in the alkaline processingcomposition or may be located in the photographic element (or in a coversheet or receiving element) in its "blocked" precursor form.

It will be appreciated that, after processing the photographic elementdescribed above, there remains in the element, after transfer has takenplace, an imagewise distribution of dye in addition to developed silver.A color image comprising residual nondiffusible compound may be obtainedin this element if the residual silver and silver halide are removed inany conventional manner well known to those skilled in the photographicart, such as a bleach bath followed by a fix bath, a bleach-fix bath,etc. The imagewise distribution of dye may also diffuse out of thiselement into these baths, if desired, rather than to an image-receivingelement.

The photographic element in the above-described process can be treatedwith an alkaline processing composition to effect or initiatedevelopment in any manner. A preferred method for applying processingcomposition is by use of a rupturable container or pod which containsthe composition. The processing composition employed in this inventioncan contain the ETA for development, although the composition could alsobe solely an alkaline solution where the ETA is incorporated in thephotographic element, the image-receiving element or the cover sheet. Inthese instances, the alkaline solution serves to activate theincorporated ETA.

A photographic assemblage or film unit in accordance with this inventionis adapted to be processed by an alkaline processing composition, andcomprises:

(1) a photographic element comprising a support having thereon at leastone photosensitive silver halide emulsion layer having associatedtherewith a dye image-providing material; and

(2) a dye image-receiving layer, the assemblage containing the ETA orprecursor thereof as described above. In this embodiment, the processingcomposition may be inserted into the film unit such as by interjectingprocessing solution with communicating members similar to hypodermicsyringes which are attached either to a camera of camera cartridge. Theprocessing composition may also be applied by means of a swab or bydipping in a bath, if so desired. In a preferred embodiment of theinvention, the assemblage itself contains the alkaline processingcomposition and means containing same for discharge within the filmunit, such as a rupturable container which is adapted to be positionedduring processing of the film unit so that a compressive force appliedto the container by pressure-applying members, such as would be found ina camera designed for in-camera processing, will effect a discharge ofthe container's contents within the film unit. As previously described,the ETA can be located in the assemblage in the processing composition.Alternatively, an ETA precursor can be located in the photographicelement or in an image-receiving element, cover sheet or process sheet,as described previously.

The dye image-providing material useful in this invention is eitherpositive- or negative-working, and is either initially mobile orimmobile in the photographic element during processing with an alkalinecompositon. Examples of initially mobile, positive-working dyeimage-providing materials useful in this invention are described in U.S.Pat. Nos. 2,983,606; 3,536,739; 3,705,184; 3,482,972; 2,756,142;3,880,658 and 3,854,985. Examples of negative-working dyeimage-providing materials useful in this invention include conventionalcouplers which react with oxidized aromatic primary amino colordeveloping agents to produce or release a dye such as those described,for example, in U.S. Pat. No. 3,227,550 and Canadian Pat. No. 602,607.In a preferred embodiment of this invention, the dye image-providingmaterial is a ballasted, redox-dye-releasing (RDR) compound. Suchcompounds are well known to those skilled in the art and are, generallyspeaking, compounds which will react with oxidized or unoxidizeddeveloping agent or electron transfer agent to release a dye. Suchnondiffusible RDR's include negative-working compounds, as described inU.S. Pat. Nos. 3,728,113 or Becker et al; 3,725,062 of Anderson and Lum;3,698,897 of Gompf and Lum; 3,628,952 of Puschel et al; 3,443,939 and3,443,940 of Bloom et al; 4,053,312 of Fleckenstein; 4,076,529 ofFleckenstein et al; 4,055,428 of Koyama et al; 4,149,892 of Deguchi etal; 4,198,235 and 4,179,291 of Vetter et al; Research Disclosure 15157,November, 1976 and Research Disclosure 15654, April, 1977. Suchnondiffusible RDR's also include positive-working compounds, asdescribed in U.S. Pat. Nos. 3,980,479; 4,139,379; 4,139,389; 4,199,354,4,232,107, 4,199,355 and German Pat. Nos. 2,854,946, the disclosures ofwhich are hereby incorporated by reference.

In a preferred embodiment of this invention, positive-working quinoneRDR's or PRDR's, are employed and the photographic element contains anincorporated reducing agent as described in U.S. Pat. Nos. 4,139,379,referred to above. In this embodiment, the quinone PRDR compound asincorporated in a photographic element is incapable of releasing adiffusible dye. However, during photographic processing under alkalineconditions, the compound is capable of accepting at least one electron(i.e., being reduced) and thereafter releases a diffusible dye. Furtherdetails are found in U.S. Pat. No. 4,139,379, the disclosure of which ishereby incorporated by reference. These quinone PRDR's have the formula:##STR8## wherein: Ballast is an organic ballasting radical of suchmolecular size and configuration as to render the compound nondiffusiblein the photographic element during development in an alkaline processingcomposition;

W represents at least the atoms necessary to complete a quinone nucleus;

r is a positive integer of 1 or 2;

R⁴ is an alkyl radical having 1 to about 40 carbon atoms or an arylradical having 6 to about 40 carbon atoms; p1 k is a positive integer of1 to 2 and is 2 when R⁴ is a radical of less than 8 carbon atoms; and

Dye is an organic dye or dye precursor moiety.

In this invention, dye image-providing materials can be used whichproduce diffusible dye images as a function of development. Eitherconventional negative-working or direct-positive silver halide emulsionsmay be employed. If the silver halide emulsion employed is adirect-positive silver halide emulsion, such as an internal-imageemulsion designed for use in the internal image reversal process, or afogged, direct-positive emulsion such as a solarizing emulsion, which isdevelopable in unexposed areas, a positive image can be obtained on thedye image-receiving layer by using ballasted, redox dye-releasers. Afterexposure of the film unit, the alkaline processing composition permeatesthe various layers to initiate development of the exposed photosensitivesilver halide emulsion layers. The ETA present in the film unit developseach of the silver halide emulsion layers in the unexposed areas (sincethe silver halide emulsions are direct-positive ones), thus causing theETA to become oxidized imagewise corresponding to the unexposed areas ofthe direct-positive silver halide emulsion layers. The oxidized ETA thencross-oxidizes the dye-releasing compounds and the oxidized form of thecompounds then undergoes a base-catalyzed reaction to release the dyesimagewise as a function of the imagewise exposure of each of the silverhalide emulsion layers. At least a portion of the imagewisedistributions of diffusible dyes diffuse to the image-receiving layer toform a positive image of the original subject. After being contacted bythe alkaline processing composition, a pH-lowering layer in the filmunit or image-receiving unit lowers the pH of the film unit or imagereceiver to stabilize the image.

Internal-image silver halide emulsions useful in this invention aredescribed more fully in the November 1976 edition of ResearchDisclosure, pages 76 through 79, the disclosure of which is herebyincorporated by reference.

The dye image-receiving layer in the above-described film assemblage isoptionally located on a separate support adapted to be superposed on thephotographic element after exposure thereof. Such image-receivingelements are generally disclosed, for example, in U.S. Pat. No.3,362,819. In accordance with this embodiment of the invention, the dyeimage-receiving element would comprise a support having thereon, insequence, a neutralizing layer, a timing layer and a dye image-receivinglayer. When the means for discharging the processing composition is arupturable container, it is usually positioned in relation to thephotographic element and the image-receiving element so that acompressive force applied to the container by pressure-applying members,such as would be found in a typical camera used for in-cameraprocessing, will effect a discharge of the container's contents betweenthe image-receiving element and the outermost layer of the photographicelement. After processing, the dye image-receiving element is separatedfrom the photographic element.

In another embodiment, the dye image-receiving layer in theabove-described film assemblage is located integral with thephotographic element and is located between the support and thelowermost photosensitive silver halide emulsion layer. One useful formatfor integral imaging receiver photographic elements is disclosed inBelgian Pat. No. 757,960. In such an embodiment, the support for thephotographic element is transparent and is coated with animage-receiving layer, a substantially opaque light-reflective layer,e.g., TiO₂, and then the photosensitive layer or layers described above.After exposure of the photographic element, a rupturable containercontaining an alkaline processing composition and an opaque processsheet are brought into superposed position. Pressure-applying members inthe camera rupture the container and spread processing composition overthe photographic element as the film unit is withdrawn from the camera.The processing composition develops each exposed silver halide emulsionlayer, and dye images, formed as a function of development, diffuse tothe image-receiving layer to provide a positive, right-reading imagewhich is viewed through the transparent support on the opaque reflectinglayer background. For other details concerning the format of thisparticular integral film unit, reference is made to the above-mentionedBelgian Pat. No. 757,960.

Another format for integral imaging receiver photographic elements inwhich the present invention is employed is disclosed in Canadian Pat.No. 928,559. In this embodiment, the support for the photographicelement is transparent and is coated with the image-receiving layer, asubstantially opaque, light-reflective layer and the photosensitivelayer or layers described above. A rupturable container, containing analkaline processing composition including an ETA and an opacifier, ispositioned between the top layer and a transparent cover sheet which hasthereon, in sequence, a neutralizing layer and a timing layer. The filmunit is placed in a camera, exposed through the transparent cover sheetand then passed through a pair of pressure-applying members in thecamera as it is being removed therefrom. The pressure-applying membersrupture the container and spread processing composition and opacifierover the negative portion of the film unit to render itlight-insensitive. The processing composition develops each silverhalide layer and dye images, formed as a result of development, diffuseto the image-receiving layer to provide a positive, right-reading imagewhich is viewed through the transparent support on the opaque reflectinglayer background. For further details concerning the format of thisparticular integral film unit, reference is made to the above-mentionedCanadian Pat. No. 928,559.

Still other useful integral formats in which this invention can beemployed are described in U.S. Pat. Nos. 3,415,644; 3,415,645;3,415,646; 3,647,437 and 3,635,707. In most of these formats, aphotosensitive silver halide emulsion is coated on an opaque support anda dye image-receiving layer is located on a separate transparent supportsuperposed over the layer outermost from the opaque support. Inaddition, this transparent support also contains a neutralizing layerand a timing layer underneath the dye image-receiving layer.

In another embodiment of the invention, the neutralizing layer andtiming layer are located underneath the photosensitive layer or layers.In that embodiment, the photographic element would comprise a supporthaving thereon, in sequence, a neutralizing layer, a timing layer and atleast one photosensitive silver halide emulsion layer having associatedtherewith a dye image-providing material. A dye image-receiving layerwould be provided on a second support with the processing compositionbeing applied therebetween. This format could either be peel-apart orintegral, as described above.

The film unit or assemblage of the present invention is used to producepositive images in single or multicolors. In a three-color system, eachsilver halide emulsion layer of the film assembly will have associatedtherewith a dye image-providing material which releases a dye possessinga predominant spectral absorption within the region of the visiblespectrum to which said silver halide emulsion is sensitive, i.e., theblue-sensitive silver halide emulsion layer will have a yellow dyeimage-providing material associated therewith, the green-sensitivesilver halide emulsion layer will have a magenta dye image-providingmaterial associated therewith and the red-sensitive silver halideemulsion layer will have a cyan dye image-providing material associatedtherewith. The dye image-providing material associated with each silverhalide emulsion layer is contained either in the silver halide emulsionlayer itself or in a layer contiguous to the silver halide emulsionlayer, i.e., the dye image-providing material can be coated in aseparate layer underneath the silver halide emulsion layer with respectto the exposure direction.

The concentration of the dye image-providing material that is employedin the present invention can be varied over a wide range, depending uponthe particular compound employed and the results desired. For example, adye image-providing material coated in a layer at a concentration of 0.1to 3 g/m² has been found to be useful. The dye image-providing materialcan be dispersed in a hydrophilic film-forming natural material orsynthetic polymer, such as gelatin, polyvinyl alcohol, etc, which isadapted to be permeated by aqueous alkaline processing composition.

The various silver halide emulsion layers of a color film assemblyemployed in this invention can be disposed in the usual order, i.e., theblue-sensitive silver halide emulsion layer first with respect to theexposure side, followed by the green-sensitive and red-sensitive silverhalide emulsion layers. If desired, a yellow dye layer or a yellowcolloidal silver layer can be present between the blue-sensitive andgreen-sensitive silver halide emulsion layers for absorbing or filteringblue radiation that is transmitted through the blue-sensitive layer. Ifdesired, the selectively sensitized silver halide emulsion layers can bedisposed in a different order, e.g., the blue-sensitive layer first withrespect to the exposure side, followed by the red-sensitive andgreen-sensitive layers.

The rupturable container employed in certain embodiments of thisinvention is disclosed in U.S. Pat. Nos. 2,543,181; 2,643,886;2,653,732; 2,723,051; 3,056,492; 3,056,491 and 3,152,515. In general,such containers comprise a rectangular sheet of fluid-and air-imperviousmaterial folded longitudinally upon itself to form two walls which aresealed to one another along their longitudinal and end margins to form acavity in which processing solution is contained.

Generally speaking, except where noted otherwise, the silver halideemulsion layers employed in the invention comprise photosensitive silverhalide dispersed together with the dye image-providing material ingelatin or another aqueous alkaline solution-permeable polymeric binderand are about 0.6 to 7 microns in thickness; and the alkalinesolution-permeable polymeric interlayers, e.g., gelatin, are about 0.2to 5 microns in thickness. Of course, these thicknesses are approximateonly and can be modified according to the product desired. The silverhalide emulsions and dye releasers may also be coated in separatelayers, if desired.

Scavengers for oxidized developing agents can be employed in variousinterlayers of the photographic elements of the invention. Suitablematerials are disclosed on page 83 of the November 1976 edition ofResearch Disclosure, the disclosure of which is hereby incorporated byreference.

Any material is useful as the image-receiving layer in this invention,as long as the desired function of mordanting or otherewise fixing thedye images is obtained. The particular material chosen will, of course,depend upon the dye to be mordanted. Suitable materials are disclosed onpages 80 through 82 of the November, 1976 edition of ResearchDisclosure, the disclosure of which is hereby incorporated by reference.

Use of a neutralizing material in the film assemblages of this inventionwill usually increase the stability of the transferred image. Generally,the neutralizing material will effect a reduction in the pH of the imagelayer from about 13 or 14 to at least 11 and preferably 5 to 8 within ashort time after treatment with alkali. Suitable materials and theirfunctioning are disclosed on pages 22 and 23 of the July 1974 edition ofResearch Disclosure, and pages 35 through 37 of the July 1975 edition ofResearch Disclosure, the disclosures of which are hereby incorporated byreference.

A timing or inert spacer layer can be employed in the practice of thisinvention over the neutralizing layer which "times" or controls the pHreduction as a function of the rate at which alkali diffuses through theinert spacer layer. Examples of such timing layers and their functioningare disclosed in the Research Disclosure articles mentioned in theparagraph above concerning neutralizing layers.

The alkaline processing composition employed in this invention is theconventional aqueous solution of an alkaline material, e.g, alkali metalhydroxides or carbonates such as sodium hydroxide, sodium carbonate oran amine such as diethylamine, preferably possessing a pH in excess of11, and preferably containing an ETA as described previously. Suitablematerials and addenda frequently added to such compositions aredisclosed on pages 79 and 80 of the November, 1976 edition of ResearchDisclosure, the disclosure of which is hereby incorporated by reference.

The alkaline solution permeable, substantially opaque, light-reflectivelayer employed in certain embodiments of photographic film units used inthis invention is described more fully in the November, 1976 edition ofResearch Disclosure, page 82, the disclosure of which is herebyincorporated by reference.

The supports for the photographic elements used in this invention can beany material, as long as it does not deleteriously affect thephotographic properties of the film unit and is dimensionally stable.Typical flexible sheet materials are described on page 85 of theNovember, 1976 edition of Research Disclosure, the disclosure of whichis hereby incorporated by reference.

While the invention has been described with reference to layers ofsilver halide emulsions and dye image-providing materials, dotwisecoating, such as would be obtained using a gravure printing technique,could also be employed. In this technique, small dots of blue-, green-and red-sensitive emulsions have associated therewith, respectively,dots of yellow, magenta and cyan color-providing substances. Afterdevelopment, the transferred dyes would tend to fuse together into acontinuous tone. In an alternative embodiment, the emulsions sensitiveto each of three primary regions of the spectrum can be disposed as asingle segmented layer, e.g., as by the use of microvessels as describedin Whitmore U.S. Pat. No. 4,362,806, issued Dec. 7, 1982.

The silver halide emulsions useful in this invention, bothnegative-working and direct-positive ones, are well known to thoseskilled in the art and are described in Research Disclosure, Volume 176,December, 1978, Item 17643, pages 22 and 23, "Emulsion preparation andtypes"; they are usually chemically and spectrally sensitized asdescribed on page 23, "Chemical sensitization", and "Spectralsensitization and desensitization", of the above article; they areoptionally protected against the production of fog and stabilizedagainst loss of sensitivity during keeping by employing the materialsdescribed on pages 24 and 25, "Antifoggants and stabilizers", of theabove article; they usually contain hardeners and coating aids asdescribed on page 26, "Hardeners", and pages 26 and 27, "Coating aids",of the above article; they and other layers in the photographic elementsused in this invention usually contain plasticizers, vehicles and filterdyes described on page 27, "Plasticizers and lubricants"; page 26,"Vehicles and vehicle extenders"; and pages 25 and 26, "Absorbing andscattering materials", of the above article; they and other layers inthe photographic elements used in this invention can contain addendawhich are incorporated by using the procedures described on page 27,"Methods of addition", of the above article; and they are usually coatedand dried by using the various techniques described on pages 27 and 28,"Coating and drying procedures", of the above article, the disclosuresof which are hereby incorporated by reference.

The term "nondiffusing" used herein has the meaning commonly applied tothe term in photography and denotes materials that for all practicalpurposes do not migrate or wander through organic colloid layers, suchas gelatin, in the photographic elements of the invention in an alkalinemedium and preferably when processed in a medium having a pH of 11 orgreater. The same meaning is to be attached to the term "immobile". Theterm "diffusible" as applied to the materials of this invention has theconverse meaning and denotes materials having the property of diffusingeffectively through the colloid layers of the photographic elements inan alkaline medium. "Mobile" has the same meaning as "diffusible".

The term "associated therewith" as used herein is intended to mean thatthe materials can be in either the same or different layers, so long asthe materials are accessible to one another.

The following examples are provided to further illustrate the invention.

EXAMPLE 1 Photographic Test w/PRDR's

A cover sheet was prepared by coating the following layers, in the orderrecited, on a poly(ethylene terepthalate) film support:

(1) an acid layer comprising poly(n-butyl acrylate-co-acrylic acid),(30:70 weight ratio equivalent to 140 meq. acid/m²); and

(2) a timing layer comprising a 1:1 physical mixture of the followingtwo polymers coated at 4.8 g/m² :

(a) poly(acrylonitrile-co-vinylidene chloride-co-acrylic acid) (wt.ratio 14:79:7), and

(b) a lactone polymer, partially hydrolyzed and 1-butanoltransesterified poly(vinyl acetate-co-maleic anhydride) (ratio ofacid/butyl ester 15:85).

(A) An integral imaging-receiver (IIR) element was prepared by coatingthe following layers in the order recited on a transparent poly(ethyleneterephthalate) film support. Quantities are parenthetically given ingrams per square meter, unless otherwise stated.

(1) metal containing layer of nickel sulfate·6H₂ O (0.58) and gelatin(1.1);

(2) image-receiving layer of poly(4-vinylpyridine) (2.2) and gelatin(2.2);

(3) reflecting layer of titanium dioxide (16.0) and gelatin (2.6);

(4) opaque layer of carbon black (1.9) and gelatin (1.2);

(5) interlayer of gelatin (1.2);

(6) red-sensitive, negative-working silver bromoiodide emulsion (1.3silver), gelatin (2.2), cyan PRDR-I (0.55), incorporated reducing agentIRA (0.29), and inhibitor (0.02); and

(7) overcoat layer of gelatin (0.87).

(B) Another element similar to (A) was prepared except that it containedcyan PRDR-II instead of cyan PRDR-I in layer 6. ##STR9## Dispersed indi-n-butyl phthalate (PRDR-I:solvent 1:1) ##STR10## Dispersed indi-n-butyl phthalate (PRDR-II:solvent 1:1) ##STR11## Dispersed indiethyllauramide (Total solid:solvent 1:1) ##STR12## Dispersed indiethyllauramide (Total solid:solvent 1:1)

Pods containing the following processing composition were prepared:

    ______________________________________                                                            Pod Composition                                           ______________________________________                                        Potassium hydroxide   47.0     g                                              ETA (as specified in Table 1)                                                                       0.02     M                                              5-Methylbenzotriazole 4.0      g                                              Sodium sulfite        1.0      g                                              Carboxymethyl cellulose                                                                             35.0     g                                              Water to 1 liter                                                              ______________________________________                                    

Samples of the IIR containing either cyan PRDR-I or -II were exposed ina sensitometer through a graduated-density test object to yield afull-scale D_(max) -D_(min) image after processing with the aboveviscous processing compositions in a pod. The exposed samples wereprocessed at room temperature by rupturing a pod containing the viscousprocessing composition described above between the IIR and the coversheet described above by using a pair of juxtaposed rollers at a gap of100μ. Within 3 hours, the Status A red density of the receiver side ofthe IIR was read to give red D_(max) /D_(min) data. After 48 hoursincubation at 49° C./70% RH, the D_(min) of the sample was read again.The ΔR D_(min) increase indicates the extent of post-processing dyediffuson. The following results were obtained:

                                      TABLE 1                                     __________________________________________________________________________     ##STR13##                                                                                        PRDR-I      PRDR-II                                                                  48 hr.      48 hr.                                 ETA                 Initial                                                                              @ 49° C.                                                                    Initial                                                                              @ 49° C.                        Com-                Red Density                                                                          70% RH                                                                             Red Density                                                                          70% RH                                 pound                                                                             A        B  D   D.sub.min                                                                         D.sub.max                                                                        ΔD.sub.min                                                                   D.sub.min                                                                        D.sub.max                                                                         ΔD.sub.min                       __________________________________________________________________________    Con-                                                                              H        H  H   0.18                                                                              1.04                                                                             +0.50                                                                              0.76                                                                             2.10                                                                              +0.26                                  trol 1                                                                        Con-                                                                              CH.sub.3 CH.sub.3                                                                         H   0.50                                                                              1.24                                                                             +0.59                                                                              1.23                                                                             1.82                                                                              +0.36                                  trol 2                                                                        Con-                                                                              CH.sub.2 OH                                                                            CH.sub.3                                                                         CH.sub.3                                                                          0.18                                                                              0.74                                                                             +0.46                                                                              0.14                                                                             1.56                                                                              +0.20                                  trol 3                                                                        Con-                                                                              CHOHCH.sub.3                                                                           CH.sub.3                                                                         H   +0.20                                                                             1.00                                                                             +0.44                                                                              0.54                                                                             2.00                                                                              +0.20                                  trol 4                                                                        Con-                                                                              CH.sub.2 CH.sub. 2 OH                                                                  CH.sub.3                                                                         CH.sub.3                                                                          0.14                                                                              0.74                                                                             +0.70                                                                              -- --  --                                     trol 5                                                                        Con-                                                                              C(OH)(CH.sub.3).sub.2                                                                  H  H   --  -- --   0.12                                                                             2.05                                                                              +0.84                                  trol 6                                                                        1   C(OH)(CH.sub.3).sub.2                                                                  H  OCH.sub.3                                                                         --  -- --   0.12                                                                             1.20                                                                              +0.04                                  2   C(OH)(CH.sub.3).sub.2                                                                  H  CH.sub.3                                                                          0.10                                                                              0.32                                                                             +0.12                                                                              0.16                                                                             2.15                                                                              +0.03                                  3   CH(OH)CH(CH.sub.3).sub.2                                                               H  CH.sub.3                                                                          0.10                                                                              0.44                                                                             +0.15                                                                              0.12                                                                             1.24                                                                              +0.10                                  4   CH(OH)C.sub.6 H.sub.5                                                                  H  CH.sub.3                                                                          0.18                                                                              1.12                                                                             +0.11                                                                              0.24                                                                             1.94                                                                              +0.05                                  5   C(OH)(CH.sub.3)C.sub.6 H.sub.5                                                         H  CH.sub.3                                                                          0.20                                                                              1.94                                                                             +0.11                                                                              0.10                                                                             0.83                                                                              0                                      6   CH.sub.2 CHOHCH.sub.3                                                                  H  CH.sub.3                                                                          0.15                                                                              0.31                                                                             +0.15                                                                              0.14                                                                             2.00                                                                              +0.12                                  7   CH.sub.2 CH.sub.2 OH                                                                   H  OCH.sub.3                                                                         --  -- --   0.13                                                                             1.18                                                                              +0.07                                  8   (CH.sub.2).sub.3 OH                                                                    H  OCH.sub.3                                                                         --  -- --   0.10                                                                             1.80                                                                              +0.06                                  9   (CH.sub.2).sub.3 OH                                                                    H  CH.sub.3                                                                          --  -- --   0.12                                                                             1.88                                                                              +0.07                                  __________________________________________________________________________

The above results indicate that the compounds according to the inventionhave much less post-processing dye diffusion (lower ΔD_(min) increases)than the control compounds which have closely related structures, suchas 3-pyrazolidinones which are unsubstituted or disubstituted at the4-position. A comparison of the results obtained with Compounds 1 and 2with the results obtained with Control 6 also illustrates the effect ofhaving an alkyl or alkoxy group on the phenyl ring.

EXAMPLE 2 Photographic Test w/Sulfonamidonaphthol RDR's

A cover sheet was prepared by coating the following layers, in the orderrecited, on a poly(ethylene terephthalate) film support:

(1) an acid layer comprising poly(n-butyl acrylate-co-acrylic acid),(30:70 weight ratio equivalent to 140 meq. acid/m²); and

(2) a timing layer comprising a mixture of cellulose acetate (40%acetyl) at 10.5 g/m² and poly(styrene-co-maleic anhydride) (50:50 wt.ratio) at 0.32 g/m². This layer also contained 0.11 g/m² of5-(2-cyanoethylthio-1-phenyltetrazole.

An IIR element was prepared by coating the following layers in the orderrecited on a transparent poly(ethylene terephthalate) film support.Quantities are parenthetically given in grams per square meter, unlessotherwise stated.

(1) image-receiving layer of apoly(styrene-co-N-benzyl-N,N-dimethyl-N-vinylbenzylammoniumchloride-co-divinylbenzene) (molar ratio 49/49/2) (2.3) and gelatin(2.3);

(2) reflecting layer of titanium dioxide (16.2) and gelatin (2.6);

(3) interlayer of gelatin (0.54);

(4) magenta dye-providing layer of Magenta RDR (0.38) and gelatin(1.08);

(5) green-sensitive, direct-positive silver bromide emulsion (0.92silver), gelatin (1.08), Nucleating Agent (0.002) and2-(2-octadecyl)-5-sulfohydroquinone (0.14); and

(6) overcoat layer of gelatin (0.86).

The direct-positive emulsion was an approximately 0.8μ monodispersed,octahedral, internal image silver bromide emulsion, as described in U.S.Pat. No. 3,923,513. ##STR14## Dispersed in 1,4-cyclohexylenedimethylbis(2-ethylhexanoate) (RDR:solvent 1:1) ##STR15##

The magenta monochrome IIR was exposed in a sensitometer through agraduated density test object to yield a full-scale D_(min) /D_(max)image after processing at 21° C. by rupturing a pod containing theviscous processing composition described below between the IIR elementand the cover sheet described above, by using a pair of juxtaposedrollers to provide a processing gap of about 65 μm.

The processing composition was as follows:

    ______________________________________                                        Potassium hydroxide   47.0     g                                              ETA (as specified in Table 2)                                                                       0.02     M                                              5-Methylbenzotriazole 4.0      g                                              Potassium sulfite     1.0      g                                              Carboxymethylcellulose                                                                              35.0     g                                              Water to 1 liter.                                                             ______________________________________                                    

After a period of not less than an hour, the reflection density of theresulting image was read to obtain D_(min) /D_(max) data.

Another sample of the IIR was left unexposed and processed in the darkto obtain maximum silver development of the internal image emulsion. Thesame pod, cover sheet, and lamination procedure was used as describedabove. Starting within 10 seconds after lamination, the infrared densityat 920 nm was read at fixed time intervals from the receiver side of theIIR to obtain the relative rate of silver development as a function oftime. The infrared density was read through the reflecting layer andthrough the dye that was released from the RDR and transferred to thereceiver without significant interference. The time required to obtainone-half the total silver density (which is proportional to dye D_(max))was determined. This relative development rate is a measure of theefficiency of the ETA to develop silver (with subsequent release ofdye). The shorter the time, the more rapid and effective thedevelopment. The following results were obtained:

                  TABLE 2                                                         ______________________________________                                                 Relative      Green Density                                          ETA Compound                                                                             Development Rate                                                                              D.sub.min                                                                             D.sub.max                                  ______________________________________                                        Control 1* 39              0.23    1.6                                        Control 2* 45              0.20    2.0                                        Control 3* 22              0.22    1.6                                        Compound 1 15              0.24    1.7                                        Compound 2 22              0.22    1.3                                        Compound 3 19              0.22    1.5                                        Compound 4 23              0.20    1.5                                        Compound 5 20              0.20    1.8                                        Compound 6 29              0.20    1.5                                        Compound 7 21              0.22    1.2                                        Compound 8 16              0.20    1.1                                        Compound 9 27              0.21    1.7                                        ______________________________________                                         *See Example 1                                                           

The above results indicate that the ETA's of this invention have eithera better relative development rate, an equal or lower D_(min), or both,than the control ETA's and give adequate imaging (higher D_(max) isobtainable through optimization).

EXAMPLE 3 Synthesis of Compound 2,4-(1-hydroxy-1-methylethyl)-1-p-tolyl-3-pyrazolidinone

To a stirred solution under nitrogen of 1-p-tolyl-3-pyrazolidinone (52.8g, 0.30 mole) in 500 ml toluene and 50 ml anhydrous tetrahydrofuran wasadded sequentially t-butyl-dimethylsilyl chloride (49.5 g, 0.30 mole),triethylamine (33.0 g, 0.30 mole), 4-(N,N-dimethylamino)pyridine (0.1 g)and 1,8-diazabicyclo[5.4.0]-undec-7-ene (0.1 g). The mixture wasrefluxed for 3 hours, then cooled to 30° C., and filtered. After thesolids were washed with ether, the solvents of the combined filtratewere removed under reduced pressure. The resulting solid was dissolvedin 500 ml anhydrous ether and filtered to remove salts. Removal of thesolvent of the filtrate yielded 85.6 g (98% yield) of1-p-tolyl-3-(t-butyldimethylsiloxy)-2-pyrazoline.

A solution of 1-p-tolyl-3-(t-butyldimethylsiloxy)-pyrazoline (218 g,0.75 mole) in 750 ml anhydrous tetrahydrofuran was added dropwise over a30 minute period to a solution of n-butyllithium (51.5 g, 0.80 mole) in350 ml n-hexane and 3.0 l anhydrous tetrahydrofuran stirred undernitrogen and cooled to -78° C. in a dry ice-acetone bath. The mixturewas stirred for another 30 minutes then treated with one portion ofacetone (58. g, 1.0 mole), and stirred at -78° C. for an additional 30minutes. After removal of the dry ice-acetone bath, one portion of 250ml 5% aqueous hydrochloric acid was added and the mixture was stirred anadditional 25 minutes. The mixture was extracted with 1.0 l of ether andthen with a (1:1) mixture of ether and ethyl acetate. The combinedextracts were dried over magnesium sulfate. After removal of solvent,the residue was digested in a hot (3:2) mixture of ether and n-hexane.Upon cooling to 0° C. and filtering, 111 g of4-(1-hydroxy-1-methylethyl)-1-p-tolyl-3-pyrazolidinone was obtained.Analysis was confirmed by infrared and NMR spectra.

EXAMPLE 4 Synthesis of Compound 9,4-(3-hydroxypropyl-1-p-tolyl-3-pyrazolidinone

To a stirred room-temperature solution under nitrogen oft-butyldimethylsilyl chloride (49.7 g, 0.30 mole) and imidazole (51.0 g,0.75 mole) in 100 ml N,N-dimethyl-formamide was added in one portion3-bromopropanol (41.7 g, 0.30 mole). The slightly exothermic reactionmixture was stirred for 3 hours, diluted with ice-water, and extractedthree times with 200 ml portions of ether. The combined ether extractswere washed five times with 100 ml portions of water and dried overanhydrous magnesium sulfate. After removal of solvent, the residue wasdistilled under reduced pressure to yield 43.0 g of a clear oil,3-bromo-1-(t-butyldimethylsiloxy)propane.

A solution of 1-p-tolyl-3-(t-butyldimethylsiloxy)-2-pyrazoline 11.6 g,0.040 mole), prepared as in Example 3, in 80 ml anhydroustetrahydrofuran was added dropwise over a 10 minute period to a stirredsolution at -78° C. of lithium diisopropylamide in 50. ml anhydroustetrahydrofuran under nitrogen (note: the lithium diisopropylamide wasgenerated at 0° C. by mixing 5.1 g diisopropylamine and 3.2 gn-butyllithium in 21 ml of n-hexane). The resulting orange-red solutionwas allowed to stir for 30 minutes at -78° C., and was then treated witha single portion of 3-bromo-1-(t-butyldimethylsiloxy)propane (10. g,0.040 mole) dissolved in 40. ml anhydrous tetrahydrofuran. After beingallowed to warm to room temperature overnight, the mixture was dilutedwith 150 ml ether and 100 ml 10% aqueous hydrochloric acid and shakenvigorously. The separated aqueous layer was extracted with a (1:1)mixture of ether and ethyl acetate. The combined extracts were driedover magnesium sulfate. After removal of solvent the residue waschromatographed on a silica column and eluted with (70:30) hexane:ethylacetate. A first fraction of 5.0 g (representing "4-monoalkylated"product), and third fraction of 2.8 g of product4-(3-hydroxypropyl)-1-p-tolyl-3-pyrazolidinone were obtained. A secondfraction of 1.0 g of "4,4-dialkylated" material was discarded. A totalyield of 66% could be considered after hydrolysis of the first fraction.

The first fraction (1.5 g) was dissolved in 100 ml tetrahydrofuran,stirred under nitrogen at room temperature, and heated sequentially with10 ml water and 0.5 ml trifluoroacetic acid. After two hours stirringthe mixture was diluted with 200 ml ether, washed sequentially withwater, ice cold saturated aqueous sodium bicarbonate, and saturatedaqueous sodium chloride, and then dried over anhydrous magnesiumsulfate. After removal of solvent, the oily residue was chromatographedon a silica column and eluted with (80:20:2) methylene chloride, ether,ethanol. After recrystallization from 1:1 toluene and ether, 0.9 g ofproduct 4-(3-hydroxypropyl)-1-p-tolyl-3-pyrazolidinone was obtained.Analysis was confirmed by NMR spectra.

The above synthesis examples are provided for illustration only and areclaimed in Michno U.S. Application Ser. No. 520,283, filed of even dateherewith, referred to above.

While specific utility for the compounds of this invention has beendescribed for image transfer systems, these compounds would also beuseful as developing agents in conventional black-and-white and colorsystems.

The invention has been described in detail with particular reference topreferred embodiments thereof, but it will be understood that variationsand modifications can be effected within the spirit and scope of theinvention.

What is claimed is:
 1. In a photographic assemblage to be processed byan alkaline processing composition, said assemblage comprising:(a) aphotosensitive element comprising a support having thereon at least onephotosensitive silver halide emulsion layer having associated therewitha dye image-providing material; and (b) a dye image-receiving layer;theimprovement wherein said assemblage contains a silver halide electrontransfer agent or precursor thereof having the following formula:##STR16## wherein: n is 0, 1 or 2; R represents hydrogen or ahydrolyzable moiety; R¹ and R² each independently represents hydrogen,an alkyl or substituted alkyl group of 1 to about 6 carbon atoms, anaryl or substituted aryl group of 6 to about 10 carbon atoms, or anaralkyl group of 6 to about 10 carbon atoms, with the proviso that whenn is 0, then either R¹ or R², but not both, may be hydrogen; and R³represents at least one alkyl or alkoxy group having from 1 to about 6carbon atoms, methylenedioxy group or ethylenedioxy group.
 2. Theassemblage of claim 1 which also contains an alkaline processingcomposition and means containing same for discharge within saidassemblage.
 3. The assemblage of claim 2 wherein R is hydrogen and saidelectron transfer agent is located in said alkaline processingcomposition.
 4. The assemblage of claim 3 wherein R¹ is hydrogen ormethyl.
 5. The assemblage of claim 3 wherein R² is hydrogen, methyl,isopropyl or phenyl.
 6. The assemblage of claim 3 wherein R³ is eithermethyl or methoxy located in the para-position.
 7. The assemblage ofclaim 2 wherein:(a) said dye image-receiving layer is located in saidphotosensitive element between said support and said silver halideemulsion layer; and (b) said assemblage also includes a transparentcover sheet over the layer outermost from said support.
 8. Theassemblage of claim 7 wherein said transparent cover sheet is coatedwith, in sequence, a neutralizing layer and a timing layer.
 9. Theassemblage of claim 8 wherein said discharging means is a rupturablecontainer containing said alkaline processing composition and anopacifying agent, said container being so positioned during processingof said assemblage that a compressive force applied to said containerwill effect a discharge of the container's contents between saidtransparent sheet and the layer outermost from said support.
 10. Theassemblage of claim 2 wherein said support of said photosensitiveelement is opaque, and said dye image-receiving layer is located on aseparate transparent support superposed on the layer outermost from saidopaque support.
 11. The assemblage of claim 10 wherein said transparentsupport has thereon, in sequence, a neutralizing layer, a timing layerand said dye image-receiving layer.
 12. The assemblage of claim 10wherein said opaque support has thereon, in sequence, a neutralizinglayer, a timing layer and said silver halide emulsion layer.
 13. Theassemblage of claim 2 wherein said dye image-providing material is apositive-working redox dye-releaser.
 14. The assemblage of claim 13wherein said positive-working redox dye-releaser is a quinone redoxdye-releaser and said photosensitive element contains an incorporatedreducing agent.
 15. The assemblage of claim 14 wherein said quinoneredox dye-releaser has the formula: ##STR17## wherein: Ballast is anorganic ballasting radical of such molecular size and configuration asto render said compound nondiffusible in said photosensitive elementduring development in said alkaline processing composition;W representsat least the atoms necessary to complete a quinone nucleus; r is apositive integer of 1 or 2; R⁴ is an alkyl radical having 1 to about 40carbon atoms or an aryl radical having 6 to about 40 carbon atoms; k isa positive integer of 1 to 2 and is 2 when R⁴ is a radical of less than8 carbon atoms; and Dye is an organic dye or dye precursor moiety. 16.The assemblage of claim 2 wherein said photosensitive element comprisesa support having thereon a red-sensitive silver halide emulsion layerhaving a cyan dye image-providing material associated therewith, agreen-sensitive silver halide emulsion layer having a magenta dyeimage-providing material associated therewith, and a blue-sensitivesilver halide emulsion layer having a yellow dye image-providingmaterial associated therewith.
 17. In an integral photographicassemblage comprising:(a) a photosensitive element comprising atransparent support having thereon the following layers in sequence: adye image-receiving layer; an alkaline solution-permeable,light-reflective layer; an alkaline solution-permeable, opaque layer; ared-sensitive, negative-working silver halide emulsion layer having apositive-working redox cyan dye-releaser associated therewith; agreen-sensitive, negative-working silver halide emulsion layer having apositive-working redox magenta dye-releaser associated therewith; and ablue-sensitive, negative-working silver halide emulsion layer having apositive-working redox yellow dye-releaser associated therewith; (b) atransparent cover sheet superposed over said blue-sensitive silverhalide emulsion layer and comprising a transparent support havingtherein, in sequence, a neutralizing layer and a timing layer; and (c) arupturable container containing an alkaline processing composition andan opacifying agent, said container being so positioned duringprocessing of said assemblage that a compressive force applied to saidcontainer will effect a discharge of the container's contents betweensaid transparent cover sheet and said blue-sensitive silver halideemulsion layer;the improvement wherein said assemblage contains a silverhalide electron transfer agent or precursor thereof having the followingformula: ##STR18## wherein: n is 0, 1 or 2; R represents hydrogen or ahydrolyzable moiety; R¹ and R² each independently represents hydrogen,an alkyl or substituted alkyl group of 1 to about 6 carbon atoms, anaryl or substituted aryl group of 6 to about 10 carbon atoms, or anaralkyl group of 6 to about 10 carbon atoms, with the proviso that whenn is 0, then either R¹ or R², but not both, may be hydrogen; and R³represents at least one alkyl or alkoxy group having from 1 to about 6carbon atoms, methylenedioxy group or ethylenedioxy group.
 18. Theassemblage of claim 17 wherein R is hydrogen and said electron transferagent is located in said alkaline processing composition.
 19. Theassemblage of claim 18 wherein R¹ is hydrogen or methyl.
 20. Theassemblage of claim 18 wherein R² is hydrogen, methyl, isopropyl orphenyl.
 21. The assemblage of claim 18 wherein R³ is either methyl ormethoxy located in the para-position.
 22. In a photographic elementcomprising a support having thereon at least one photosensitive silverhalide emulsion layer having associated therewith a dye image-providingmaterial, the improvement wherein said element contains a silver halideelectron transfer agent precursor having the following formula:##STR19## wherein: n is 0, 1 or 2;R¹ and R² each independentlyrepresents hydrogen, an alkyl or substituted alkyl group of 1 to about 6carbon atoms, an aryl or substituted aryl group of 6 to about 10 carbonatoms, or an aralkyl group of 6 to about 10 carbon atoms, with theproviso that when n is 0, then either R¹ or R², but not both, may behydrogen; R³ represents at least one alkyl or alkoxy group having from 1to about 6 carbon atoms, methylenedioxy group or ethylenedioxy group;and R⁵ is a hydrolyzable moiety.
 23. The photographic element of claim22 wherein R¹ is hydrogen or methyl.
 24. The photographic element ofclaim 22 wherein R² is hydrogen, methyl, isopropyl or phenyl.
 25. Thephotographic element of claim 22 wherein R³ is either methyl or methoxylocated in the para-position.
 26. The photographic element of claim 22wherein said dye image-providing material is a positive-working redoxdye-releaser.
 27. The photographic element of claim 22 which comprises asupport having thereon a red-sensitive silver halide emulsion layerhaving a cyan dye image-providing material associated therewith, agreen-sensitive silver halide emulsion layer having a magenta dyeimage-providing material associated therewith, and a blue-sensitivesilver halide emulsion layer having a yellow dye image-providingmaterial associated therewith.